Cyanuric Acid Trace Analysis by Extractive Methylation via Phase-Transfer Catalysis and Capillary Gas Chromatography Coupled with Flame Thermoionic and Mass-Selective Detection. Process Parameter Studies and Kinetics

A GC method using phase-transfer catalysis for the simultaneous derivatization, extraction, and preconcentration of the highly polar cyanuric acid (CYA) was developed. The method was based on the extractive N-methylation of the analyte of concern in two- and three-phase systems, whereby the 1,3,5-trimethyl-1,3,5-triazine-2,4,6-(1H,3H,5H)trione was formed. Subsequent detection was performed using flame thermoionic specific detection (FTD) and mass spectrometry (MS) selective-ion monitoring (SIM) using electron impact. The optimal experimental conditions related to pH, kind of catalyst and solvents, methyl iodide concentration, phase volumes, reaction time, temperature, and agitation were suitably established. Inter alia, the resulting method is highly sensitive, almost free from interferences, and was easily applied to the determination of cyanuric acid in swimming pool water, surface water, human urine, and simulated air filter samples. The minimal quantitable concentration was found to be less than 1 and 90 (mu)g L^-1using GC-MS(SIM) and GC-FTD, respectively. The overall precision for the workup procedure did not exceed 3.6% (n = 6) for 5.0 (mu)g L^-1CYA-spiked urine and river water while the respective value for the same matrixes spiked at a concentration of 200 (mu)g L^-1was calculated to be in the range 1.94.0% (n = 6). The overall recovery from spiked samples was 98 +- 5% for microgram per liter levels of CYA. A kinetic study conducted was helpful to get a better insight into the N-methylation reaction mechanism.